Pressure control system for g-suit

ABSTRACT

A control system for a G-suit having an acceleration signal and a time rate of change of the acceleration signal supplied to a summing circuit with the output of the summing circuit being supplied to a comparator through a function generator circuit. The function generator output is compared with a reference level in the comparator circuit with the output of the comparator being used to energize a relay that controls a solenoid between the air supply and the G-suit. The function generator programs pressure to the G-suit according to a particular function of the output signal of the summing circuit. A pressure signal from the pressure suit and rate of change in suit pressure signal are summed in a second summing circuit with the output of the second summing circuit being used as a third input to the comparator circuit.

United States Patent Van Patten et a].

[ Dec. 25, 1973 PRESSURE CONTROL SYSTEM FOR 3,719,193 3/1973 Boyle137/38 G-SUIT Primary ExaminerWilliam E. Kamm [75] Inventors: Robert E.Van Patten, Kettermg,

Ohio; Dana B- g y, Attorney Harry A. Herbert, Jr. et al. Mass' 57ABSTRACT [73] Asslgneei The United states of Amer'ca as A control systemfor a G-suit having an acceleration repmsemed by f Secretary 0f thesignal and a time rate of change of the acceleration Air Force washmgtomsignal supplied to a summing circuit with the output of 22 Filed; July18, 7 the summing circuit being supplied to a comparator through afunction generator circuit. The function [21 1 Appl' N05 273,005generator output is compared with a reference level in the comparatorcircuit with the output of the compar- 52 us. 01. 128/1 A, 137/38 atorbeing used to energize a relay that controls a sole- 511 Int. Cl. A6lt5/37 noid between the air pp y and the The func- 5 Field of Search 128/1A, 1 R, 142.5, tioh generator Programs pressure-t0 the G-suit accord- 20 5; 137/38 81 ing to a particular function of the output signal of thesumming circuit. A pressure signal from the pressure 5 References Citedsuit and rate of change in suit pressure signal are UNITED STATESPATENTS summed in a second summing circuit with the output of the secondsumming circuit being used as a third yea-(3232c 137/38 input to thecomparator circuit 3,089,482 5/1963 Gray 128/1 A 2 Claims, 3 DrawingFigures flfffff/VCE sap/us! l 2a 23 /s COMPHIJIU! flc K jig 3 2 gZ l Emean. S06Wal0| v I Ks l 22 7 26 Sl/NM/N i as PATENTEB DEC 2 51975 Baa W-Ff PRESSURE CONTROL SYSTEM FOR G-SUIT BACKGROUND OF THE INVENTIONCurrent G-suit valves are mechanical devices which require a certainacceleration in order to operate. It is necessary to design the valvesso that they are not operated by transient accelerations, so that thepilot or aircrewman is not distracted by transient inflations.Therefore, when protection is required, the valve does not operate untilafter the pilot has already been subjected to an acceleration for sometime in an unprotected condition.

BRIEF SUMMARY OF THE INVENTION According to this invention, the delay inthe initiation of protection is solved by providing an electronic systemwhich takes both the acceleration level and the time rate of change ofacceleration into account, which makes it possible to initiateprotective action at an earlier time without subjecting the pilot tounnecessary transient inflations. Also, a function generator is used sothat the inflation as a function acceleration may be made to follow adesired pattern. Thus, it is possible to initiate protective action atan earlier time so as to increase the pilots ability to toleratesustained acceleration stress such as may be encountered in combatmaneuver situations.

IN THE DRAWING FIG. 1 is a circuit schematic in block form, of a valvecontrol system for G-suits.

FIG. 2 is a circuit schematic of one type of function generator that maybe used with the device of FIG. 1.

FIG. 3 shows the characteristic of E vs E for the device of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to FIG. 1 ofthe drawing which shows a control system for a G-suit indicatedschematically at 12. An air control solenoid 14 which controls the flowof air from an air supply 15 to the G- suit 12 is controlled by a relay16 in response to the output from comparator circuit 18. The comparator18 may be a conventional summing operational amplifier used as acomparator.

The output of an accelerometer 20 is supplied to the summing circuit 22through amplifier 23. A time rate of change of the accelerometer outputis also supplied to the summing circuit 22 from differentiating circuit25.

The output of the summing circuit is fed to a function generator 26,such as shown in FIG. 2, which provides an output as a function of inputas shown in FIG. 3.

Other function generators than that shown may be used. For example, thefunction generator on page 374 of EAI Handbook of Analog Computation"may be adapted for use with device of the invention when it is desiredto have a short rest period between two rising periods. Other functiongenerators may be provided to make inflation as a function ofacceleration follow any desired sequence. The diodes D D and D conductwhen the supply voltages, set in adjustable D.C. supplies 28, 28 and28", are exceeded which sets the break point in the characteristic curveshown in FIG. 3. The resistances R R and R are adjusted to control theslope. This then provides different rates of increase in suit pressurewith increase in the acceleration signal.

The resistance indicated at R. may include all or part of the impedanceof the source supplying the function generator.

The output signal of the function generator is compared in comparator 18with a reference signal from the reference level circuit 34 to preventoperation of relay 16 during transient accelerations. A suit pressuresignal and a rate of change of suit pressure signal, derived frompressure transducer 35, are supplied to a summing circuit 28 with theoutput of the summing circuit being applied as a third input tocomparator circuit In the operation of the device, the output ofaccelerometer 20 and a time rate of change of the accelerometer signalare summed in summing circuit 22 with the output of the summing circuitbeing supplied to a function generator 26. The output of the functiongenerator is compared with a predetermined reference level signal fromcircuit 34 to block transient inflations due to transient accelerations.An output from the comparator circuit 18 operates relay 16 to energizesolenoid l4 and allow air from supply 15 to flow into the pressure suit12. So that the pilot is not permitted to remain in an unprotectedcondition for any appreciable length of time, the time rate of changesignal to the summing circuit 22 can act to provide protection morerapidly in the same manner as described above.

To control the rate at which air is supplied to the pressure suit and todeenergize solenoid 14 when the proper pressure level has been reachedin the pressure suit, a pressure signal and a pressure rate signal aresupplied to a summing circuit 28, from pressure transducer 35, with theoutput of summing circuit 28 being supplied as a third input tocomparator 18. The input to comparator 18 from summing circuit 28 willhave the opposite sign than the input from function generator 26.

There is thus provided a pressure control system for a G-suit which willblock transient inflations of the G- suit but will give more immediateprotection when needed.

We claim:

l. A pressure control system for pressure suit comprising; a pressuresuit, means for providing a supply of air under pressure to saidpressure suit; means for controlling the flow of air from the air supplyto the pressure suit; said controlling means including a solenoid valveconnected between the air supply and the pressure suit; a first summingcircuit; means for supplying an acceleration responsive signal to afirst input of said summing circuit; means for supplying a signalproportional to the time rate of change of the acceleration responsivesignal to a second input of said first summing circuit; a comparatorcircuit; means for applying a signal, proportional to a certainpredetermined function of the output of said first summing circuit, to afirst input of the comparator circuit; means for supplying a referencelevel signal to a second input of said comparator circuit; a secondsumming circuit; means for supplying a signal proportional to pressurein said pressure suit to a first input to said second summing circuit;means for supplying a signal proportional to the time rate of change ofpressure in the pressure suit to a second input of said second summingcircuit; means for supplying the output of said second summing circuitto a third input of said comparator circuit; means responthe outputsignal from the first summing circuit at predetermined voltage levels ofthe first summing circuit output signal.

1. A pressure control system for pressure suit comprising; a pressuresuit, means for providing a supply of air under pressure to saidpressure suit; means for controlling the flow of air from the air supplyto the pressure suit; said controlling means including a solenoid valveconnected between the air supply and the pressure suit; a first summingcircuit; means for supplying an acceleration responsive signal to afirst input of said summing circuit; means for supplying a signalproportional to the time rate of change of the acceleration responsivesignal to a second input of said first summing circuit; a comparatorcircuit; means for applying a signal, proportional to a certainpredetermined function of the output of said first summing circuit, to afirst input of the comparator circuit; means for supplying a referencelevel signal to a second input of said comparator circuit; a secondsumming circuit; means for supplying a signal proportional to pressurein said pressure suit to a first input to said second summing circuit;means for supplying a signal proportional to the time rate of change ofpressure in the pressure suit to a second input of said second summingcircuit; means for supplying the output of said second summing circuitto a third input of said comparator circuit; means reSponsive to theoutput of said comparator circuit for controlling the operation of saidsolenoid valve.
 2. The device as recited in claim 1 wherein saidfunction generator includes means for changing the rate of increase ofsuit pressure with an increase in the level of the output signal fromthe first summing circuit at predetermined voltage levels of the firstsumming circuit output signal.